The participants for the study were 41 young, healthy, nonsmoking adults, aged 18-46, balanced by race (black/white) and gender. The protocol was similar to the pilot study except that only resting and immediately post-stress blood samples were taken. On average, plasma nitric oxide metabolite (NOx) levels did not change across the protocol, and levels were higher among men relative to women at all timepoints (p's< .05). However, changes in Nox during stress were inversely related to diastolic blood pressure (DBP) change for both the speech and the cold pressor (r's adjusted for baseline DBP = - 0.40 and 0.34, respectively, p's < .05). Although the correlations were higher among men (adjusted r's = - 0.55 for speech and 0.60 for cold pressor, p's < .01), there were no significant differences in relationships between Nox and DBP across gender, race, or family history of hypertension (n=18). This study therefore found that plasma Nox changes during stress are inversely related to DBP reactivity, consistent with previous evidence showing NO regulation of vascular reactivity and our preliminary data.